Cooling means for lifting magnet

ABSTRACT

A magnet for lifting high temperature materials is disclosed as having a metal case, an electrical winding enclosed within the metal case for producing a magnetic field and thermal insulation surrounding the winding and separating it from the metal case. A cooling medium is circulated about the winding within the thermal insulation by a cooling means which may include a pump and hose carrying the cooling medium and connecting the pump to the metal case. The thermal insulation serves to prevent the cooling medium from attempting to cool the metal case.

United States Patent Rybak [4 1 Sept. 19, 1972 [54] COOLING MEANS FOR LIFTING 3,439,304 4/1969 Palm ..335/292 X MAGNET Primary Examiner-George Harris [72] Inventor. James P. Rybak, 2996 Mount Holyoke Rd., Columbus, Ohio 43221 [22] Filed: Feb. 1, 1971 [57] ABSTRACT [21] Appl. No.: 111,563 A magnet for lifting high temperature materials is disclosed as having a metal case, an electrical winding enclosed within the metal case for producing a mag- "335/ 294/ netic field and thermal insulation surrounding the I u c n u u l n n e n e e e o n e l u I e a n e I e I e n I n o :IQI IUIII'QOII A [58] Field of g gfgb d gf 6 ing medium is circulated about the winding within the thermal insulation by a cooling means which may include a pump and hose carrying the cooling medium [56] References Cited and connecting the pump to the metal case. The ther- UMTED STATES PATENTS mal insulation serves to prevent the cooling medium 3 056 071 9/1962 Bak 36/60 x from attempting to cool the metal case.

er 3,283,278 11/1966 Palm 335/292 4 Claims, 3 Drawing Figures PUMP O 4 16 J J l l 32 7 x\l\\\\\ ;l l\ I I n\\\\ i 4 5 18 28 PATENTED SEP 19 m2 PUMP BACKGROUND OF THE INVENTION This invention relates to a lifting magnet for lifting high temperature materials and, in particular, to cooling means for maintaining the temperature of the electrical winding of the lifting magnet below a maximum operating level.

Lifting magnets are widely used for lifting high temperature magnetic materials. For example, electromagnets are used in steel millsfor lifting blooms and plates which may have temperatures as high as l,l Fahrenheit. One critical factor limiting the ability of an electro-magnet to operate while lifting such high temperature magnetic materials is the extent to which the electrical insulation system of the magnet coil can withstand damage or deterioration due to the heat. Several solutions have been offered to this problem in the past. However, none of these has been entirely successful. One of these solutions has been to use ceramic electrical insulation which would maintain the necessary degree of dielectric strength at temperatures in excess of 180 Centigrade. However, the expansion of the winding conductor, which is usually copper or aluminum, at these temperatures cannot be contained inside the magnet case due to forces caused by the differences in coefficients of linear expansion. Another prior art approach to the problem is to use an external cooling arrangement to cool both the magnet electrical winding and the magnet metal case as a unit. This arrangement has not been satisfactory due to the quantity .of thermal energy transmitted from the hot material being handled by the lifting magnet to the magnet case and subsequently to the electrical winding. The quantity of thermal energy transferred to the electrical winding cannot be removed by a practical cooling means. The most commonly used types of lifting magnets for handling hot materials have bottom plates attached to the bottom of the lifting magnet in a manner which minimizes the flow of thermal energy transferred from the hot material to the magnet and its winding. No cooling means is used and these magnets can only be used on an intermittent basis.

SUMMARY OF THE INVENTION It is an object of the invention to provide a magnet for lifting high temperature material which is operable continuously without deterioration or damage to the electrical winding of the magnet. It is another object of the invention is to provide a simple means for preventing heat from the case of the lifting magnet from reaching the electrical winding of the magnet. A more specific object of the invention is to provide a cooling arrangement for the electrical winding of a lifting magnet in which the winding and a cooling medium circulated into and out of the magnet case are both thermally isolated from the magnetcase.

The objects of the invention are accomplished by providing thermal insulation around the electrical winding of a lifting magnet between the metal case of the magnet and the winding. In this manner, a large portion of heat in the lifting magnet case will be prevented from reaching the winding. A cooling medium is circulated adjacent the electrical winding within the thermal insulation so that the relatively small amount of heat from the metal case that does reach the winding and the heat due to copper loss of the winding are removed to thereby maintain the winding within its permissible operating temperature.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a plan view of the preferred embodiment of the invention with a portion of the magnet casing broken away to show the interior insulating and cooling arrangement;

FIG. 2 shows another embodiment of the invention also with a portion broken away; and

FIG. 3 shows a third embodiment of the invention with a portion broken away.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring generally to FIG. 1, a lifting magnet is shown as having a metal case 2 which may be of steel and an electrical winding 4 positioned within the case 2. The electrical winding 4 includes insulated conductors 6, electrical insulation 8 surrounding the winding 4 and electrical insulation layer 7 between sections of winding 4.

A cooling means 20 for maintaining the electrical winding 2 within its permissible operating temperature is provided and includes tubular cooling coils l2 positioned immediately adjacent and in heat conducting relationship with the electrical winding 4. Thermal insulation 14 such as fiberglass is positioned between the magnetic case 2 and the winding 4 and surrounds the winding 4. The thermal insulation 14 thus defines the cavity 16 within which the winding 4 is positioned. A steel coil capsule 18 also surrounds the cooling coils l2 and the winding 4 to provide a moisture tight enclosure for the winding 4 and coils 12.

The cooling means 20 also includes a pump 21 for pumping or circulating the cooling medium 10 through the cooling coils 12 and flexible hose or tubing 22 connected to coils 12 for carrying the cooling medium 10 to and from the cooling coils 12. The cooling medium 10 may be a fluid, for example, air or a refrigerant such as Freon.

The metal case 2 includes flanges '26 usable for attaching the magnet to a lifting means (not shown). The metal case 2 also includes an inner pole shoe 28, an outer pole shoe 30, and a bottom plate 32. When the lifting magnet picks up and moves high temperature iron or steel, the metal case 2 and in particular the pole shoes 28 and 30 and bottom plate 32 engage the hot material and the metal case 2 quickly assumes a temperature very close to the material being handled. The thermal insulation 14 inhibits the heat in the case 2 from reaching the winding 4 and thereby heating the winding 4 far in excess of its maximum allowable operating temperature.

The lifting magnet is operated by energizing the electrical winding 4 so that a magnetic field is established through pole shoes 28 and 30. The magnet is moved adjacent to or into contact with high temperature magnetizable material by means such as a lifting boom. The magnetizable material is thereby attracted into engagement with and held against the pole shoes 28 and 30 while the material is moved to another location. Heat from the material which is conducted or radiated by the case 2 toward the winding 4 is prevented from reaching the winding 4 and the cooling medium in the coils 12 by the thermal insulation 14. The relatively small amount of heat that is radiated or conducted through the thermal insulation 14 is readily absorbed by the cooling medium 10 and conducted out of the metal casing 2.

In the embodiment shown in FIG. 2, the cooling coils 12 are eliminated and the winding 4 is supported by flanges 24 which comprise part of coil capsule 18. An open space 36 is provided between the coil capsule 18 and the electrical insulation layer 8 and the cooling medium 10 is circulated through opening 38 into the space 36 and out of opening 40 back to the pumping means 20. This arrangement permits some economy and simplification by eliminating cooling coils 12.

In the embodiment shown in FIG. 3, elements identical to the embodiment shown in FIG. 1 again are identified by the same reference numeral. In FIG. 3, the electrical winding 34 has electrically insulated hollow conductors 44 enclosed within the coil capsule l8 and the thermal insulation 14. The cooling medium 10 is circulated directly through the hollow conductors 44. This embodiment, of course, permits more efficient cooling of the winding 4 due to direct contact of the cooling medium 10 with the conductors 44.

From the foregoing it may be readily appreciated that the lifting magnet of the invention may be continuously operated at higher temperatures than any previously existing magnet used for lifting high temperature materials. This, of course, permits higher speed material handling time and accompanying lower operating costs.

While only three specific embodiments of the invention have been shown herein, it will be realized that many modifications thereof are feasible without departing from the spirit and scope of the invention. It is accordingly intended that the scope of the invention is not to be limited by the specific embodiments disclosed.

lclaim:

1. An electro-magnet for lifting high temperature material comprising an electrical winding connected to a power source and having a maximum allowable .operating temperature, a metal case enclosing the winding and having a temperature exceeding said maximum winding temperature during normal operation of the lifting magnet, means for cooling said electrical winding including a cooling medium adjacent the winding, and thermal insulation material enveloping said winding and said cooling medium, whereby heat in said case is inhibited from reaching said cooling medium and winding.

2. The combination according to claim 1 wherein said material has a temperature exceeding said maximum winding temperature and the metal case engages said material during operation of the lifting magnet whereby heat is transferred from said material to the metal case.

3. The combination according to claim 1 wherein said cooling means includes tubing positioned in heat conducting relationship with said winding and means positioned external of said metal casing and connected to the tubing for circulating said cooling medium throu hthe tubing.

4. he combination according to claim 1 wherein said metal case includes a pair of pole shoes engaging said high temperature material during operation of the lifting magnet and said cooling means includes pump means located remotely from the metal case for circulating the cooling medium through said case and hose means connected between the metal case and pump means, said cooling medium being in said hose means.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 43,693,126 DATED I September 19, 1972 |NV ENTOR(S) James P. R ybak It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover page of the patent following Item [72] Inventor and preceeding Item [22] Filing Date insert Assignee:

McGraw-Edison Company, Elgin, Il1ino1s- Signed and Sealed this Eighth Day of March 1977 [SEAL] Arrest:

RUTH C. MASON r C. MARSHALL DANN H Commissioner ufPatenrs and Trademarks UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3 ,693 ,126

DATED I September 19, 1972 INV ENTOR(S) James P. Rybak' It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover page of the patent following Item '[72] Inventor and preceeding Item [22] Filing Date lnsert -Assignee:

McGraw-Edison Company, Elgln, I1l1no1s- Bigncd and Scaled this Eighth Day of Marh 1977 [SEAL] AUBST.

RUTH C. MASON C. MARSHALL DANN 8 17 (ummissioner oj'Parems and Trademarks 

1. An electro-magnet for lifting high temperature material comprising an electrical winding connected to a power source and having a maximum allowable operating temperature, a metal case enclosing the winding and having a temperature exceeding said maximum winding temperature during normal operation of the lifting magnet, means for cooling said electrical winding including a cooling medium adjacent the winding, and thermal insulation material enveloping said winding and said cooling medium, whereby heat in said case is inhibited from reaching said cooling medium and winding.
 2. The combination according to claim 1 wherein said material has a temperature exceeding said maximum winding temperature and the metal case engages said material during operation of the lifting magnet whereby heat is transferred from said material to the metal case.
 3. The combination according to claim 1 wherein said cooling means includes tubing positioned in heat conducting relationship with said winding and means positioned external of said metal casing and connected to the tubing for circulating said cooling medium through the tubing.
 4. The combination according to claim 1 wherein said metal case includes a pair of pole shoes engaging said high temperature material during operation of the lifting magnet and said cooling means includes pump means located remotely from the metal case for circulating the cooling medium through said case and hose means connected between the metal case and pump means, said cooling medium being in said hose means. 